1. Field of the Invention
This invention relates to a device for the management of electrical cable used in mining operations to power moving mining equipment. The device winds and unwinds cable from a drum upon demand and keeps the cable out of harms way.
2. Description of the Prior Art
Almost all power utilized to operate equipment and machinery in mining operations is electrical. Mining operations require highly specialized equipment that either dump, haul, or bore tunnels into the rock or other earth strata as they move about in mining operation. These vehicles have to be moveable, and they have to have the capability of operating in confined, small locations, like mine tunnels. A typical vehicle would be a miner. A miner is a vehicle which bores into the rock, or other earth strata by the use of tools and other implements on the front of the vehicle. The rock ore that has been excavated at the front end, is conveyed to the rear of the vehicle, and dumped into other vehicles for hauling to other locations for removal to surface. These vehicles are powered by electricity from flexible cables that carry very high voltage. The fact that these vehicles are moveable requires that they be capable of being attached to an electrical cable so that they always have direct power sufficient for their operation. The handling of the cable is a major problem since the vehicles move about freely. The cable must always be handled so as to be kept clear of being run over by mining equipment and yet there must be sufficient cable available to permit travel and movement by the equipment. Typically, most mining vehicles that are electrically driven utilized manual labor, or workers, to manhandle, drag or reel the electrical cable as the machine or vehicle moves, about in the mine tunnels. Such work is dangerous, because of standing water, high voltage, and heavy cable, in addition to damage caused by mining vehicles.
There are, however, numerous known mechanical devices for spooling and/or handling electrical cables of mining vehicles as they move about in mining tunnels. All known devices have inherent defects or problems involved with their use.
The single most serious problem of known devices is the method for managing electrical cable which powers the vehicle. In most known devices, a rotating drum or reel is utilized to spool the cable. In all devices that utilize rotating drums to spool the cable, slip-rings, rotating collector rings, brushes or the like are employed to couple the power line coming and leaving the reel. Two of many examples are Dudley U.S. Pat. No. 3,061,233, and Tschurbanoff U.S. Pat. No. 4,583,700. Others employ the same technology. These slip rings and the like are potentially dangerous in mining operations. Mining regulations (see part 18.43 of 30 CFR ch 1 of Mine Safety and Administration) require that all such slip-rings and the like be contained within explosion proof boxes and even when that is done, those connectors are unreliable and severely wear prone, due to the severe environment conditions of a mine. They are also expensive, complicated, and ineffective. Additionally, the explosion proof enclosures are large and utilize excess amounts of space on the mining vehicle.
A more recent system for storing cables is described in U.S. Pat. No. 4,258,834, issued to Hawley. There, no slip-rings are employed. There, cable is dumped or pulled into or out of a large drum. The cable is fed through a round sleeve in which are disposed frictional devices which engage the cable and pull it into the drum. Hawley unlike the present invention not only can handle round cable, but flat, oblong, etc. The prior art devices make no allowance to handle other than round cable. Further the electrical cable used in Hawley is not continuous from the power source to the mining vehicle but uses slip rings or other dangerous connectors.
The device described in Hawley and other prior art patents describe a stationary drum onto which cable can be loaded by a rotating arm. The cable is supposed to stack systematically, simply by gravity and the weight of the cable. However the cable is pulled into the drum by friction type device which squeeze the cable and pull it through the feeding fair-lead. Once the cable is clamped and squeezed, it restricts twisting of the cable, so when the cable is dumped into the container, it will twist, wrinkle, and not stack in any uniform manner. Such stacking decreases the available space for storage of the cable in the drum, unlike the present invention where the cable is systematically loaded. Space in mining operations is very limited and must be kept to a minimum. Drum stacking cannot be used in mining operations. There is no method presently available to automatically manage power cables for mining operation.
Almost all mining vehicles utilize the rear of the vehicle for mining operations. In Hawley, the container and storage bin is directly behind the vehicle while the drum of the present invention is disposed away from the mining operation and vehicle. A rear stacking device can not be used in most mining vehicle applications, simply because the drum must be located in a space used for work in a mining operation. The miner, for instance, cuts rock from the front and conveyors it to the rear for dumping and hauling. In operation it is also desirable that the power cable be placed on the side of the tunnel. If the cable is positioned or unwound and placed into the middle of the tunnel it interferes with all vehicles that may be moving in or about the tunnel. The present invention permits cable to be laid out at the side of the tunnel.
Lastly, all cables have splices and most are irregular shape. The prior art devices does not provide for the various size or shaped cables while the instant invention can operate with any shape of cable or splice.
There are devices like Dudley, supra, that utilize side mounted rotating reels. However, there is no known device which use a stationary reel for the storage and unwinding and winding of electrical cables, which can be disposed away from the mining operation while permitting the mining equipment to move freely about at will. The device automatically winds or unwinds cable in response to movement and/or demand of the mining equipment.
The other significant prior art is the applicant's own U.S. Pat. No. 5,419,508. That patent has as its salient feature an oblong stationary drum that is mounted on the side of a mining vehicle. That device does use a continuous power cable and orbiting device for winding cable on the fixed drum. The device also contemplates a clutch and pneumatic control system for winding and unwinding as provided in the present invention.
The instant invention contemplates a large cable management device. It can not be disposed on mining equipment and does not utilize an oblong drum. The present device can store large quantities of large cable and need not be disposed near the actual mining operation, where the cable can be damaged and cause serious injury or destruction. The device of the present invention weighs over 5,000 lbs. and is 78 inches in height, and can not be mounted on a mining vehicle, which is a critical element of patent 5,419,508. It is instead mounted on skids.
The stationary drum must be cylindrical in the present invention and cannot be oblong as described in the prior patent. This construction will permit the storage and management of large diameter electrical cable which the prior patent cannot handle.
These and other problems of the prior art devices are resolved by the present invention, which is described hereinafter.